The present invention relates generally to hearing aids and more particularly to an in-the-ear miniaturized hearing aid of the type that has all of its electrical and mechanical elements, including a replaceable battery, contained within an earmold small enough to be positioned substantially within the ear canal.
Many different types and designs of hearing aids are presently available to assist person having hearing deficiencies. Such hearing aids typically incorporate a microphone for converting sound waves to an electrical signal which is amplified by an amplifier and a receiver for converting the amplified electric signal into amplified sound waves which are directed to the ear drum.
Miniaturization of electronic components and batteries has made possible the production of "integrated" hearing aids having all of the necessary components incorporated in a single earmold worn substantially within the ear canal. Integrated hearing aids of this type are desirable because they are lightweight and convenient to use and because they have the cosmetic advantage of being inconspicuous.
Generally in hearing aids of this type the receiver is positioned remote from the opening through the inner most tip of the earmold which is adjacent to the ear drum. The sound from the receiver is generally piped via small tubing to the earmold's inner most tip opening adjacent the ear drum.
This tubing creates several problems. Because the receiver and tube are physically attached in some way to the earmold, the mechanical vibrations generated by the receiver are transmitted directly to the earmold through both the receiver-to-earmold attachment and the tubing-to-earmold attachment. These mechanical vibrations travel through the earmold to the microphone resulting in feedback. The tubing being small in diameter is easily blocked by wax build-up preventing satisfactory hearing aid operation.
The material used to construct the tubing has a degree of acoustic transparency which further increases the aforementioned feedback problem.
Further, the tubing, because of its uniformly small diameter, does not perform satisfactory as an acoustic horn. This results in an undesirable overall frequency response.
There is a continuing need in the hearing aid art for further miniaturization, less feed back, reduced wax buildup and improved frequency response.